Basalt is a hard, dense volcanic rock that has been used as a raw material in casting processes to make tiles and slabs. Cast basalt liners are also used for steel tubing since the liners exhibit very high abrasion resistance in industrial applications. In crushed form, basalt also finds use as aggregate in concrete.
Basalt is also used for fiber reinforcement of composites and other applications where a drawn basalt filament is used to produce other articles of manufacture. Quarried basalt rock is first crushed, then washed and loaded into a bin attached to feeders that move the material into melting baths in gas-heated furnaces. As crushed basalt enters the gas-heated furnace, the material is liquefied at a temperature of approximately 1,500° C. The opaque basalt absorbs infrared energy and therefore it is more difficult for gas burners used in conventional furnaces to uniformly heat the entire basalt mix. Consequently the melting basalt must be held in the furnace for extended periods of time to ensure a homogenous temperature. Attempts to promote uniform basalt heating include immersion of electrodes in the bath. However there is a preference for gas heating despite increased manufacturing costs. An alternative two-stage gas heating scheme features separate zones equipped with independently controlled heating systems where only the temperature control system in the gas furnace outlet zone that feeds basalt filament extrusion bushings requires precision temperature control, so a less sophisticated temperature control system may be used in the initial gas heating zone. The extruded basalt filaments can then be further processed, for example, into fibers, fabrics or other articles of manufacture.
It is one object of the present invention to provide alternative apparatus and method for heating and melting of basalt to produce molten process basalt for basalt articles of manufacture.
It is another object of the present invention to provide alternative apparatus and method for heating and melting of basalt to produce molten process basalt for continuous casting of basalt articles of manufacture.
It is another object of the present invention to provide alternative apparatus and method for heating and melting of basalt for the continuous casting of basalt fiber or filament.